package corej.course.basic;

public class TestFact {
    public static void main(String[] args) {
        int number = Integer.parseInt(args[0]);
        if (number <= 0) {
            System.out.println("Error!");
            System.exit(0);
        }
        double result = 1;
        for (int i = 1; i <= number; i++) {
            result *= i;
        }
        System.out.println(number + "!=" + result);
    }
}